Reg3 dependent accumulation of macrophages in aging related atrial fibrillation

Abstract

Abstract Background The mechanisms underlying the high prevalence of AF in the elderly population are not well understood. Inflammation induced aging related AF need to be further elucidated. Purpose The aim of this study was to explore new mechanisms that inflammation induced aging related AF and provide new directions for the clinical management of the occurrence, development and recurrence of AF in the elderly. Methods SD rats fed normally until 20 months of age were constructed as the aging group.The young group (control) was SD rats fed normally until 3 months of age. Electrophysiological examination detected atrioventricular conduction circumference (AVWCL), sinus node recovery time (SNRT), refractory period (ERP) and AF inducibility. Aging rats were also divided into aging prone and non-prone AF according to AF inducibility. RNA-seq was performed on atrium. We overexpressed Reg3γ in both young and aging hearts by AAV-viurs to evaluate electrical and structural remolding, AF inducibility as well as inflammation. Bone marrow-derived macrophages (BMDMs) were isolated and induced. Migration assays, qPCR and cytokine array panel were performed to observe the effects of Reg3γ on BMDMs recruitment, production and secretion of inflammatory factors. RNA-seq and siRNA were performed on BMDMs with or without Reg3γ to investigate the mechanism of macrophage activation by Reg3γ. Results AVWCL, SNRT, AERP, AF inducibility and atrial fibrosis were increased in aging rats compared with young controls. RNA-seq analysis of AF-prone atrium in the aging group compared with those in the young group showed the differential genes were mainly concentrated in inflammation-related pathways. The mRNA level of TNFα, CCL2, CCL10 were significantly increased in aging rats. In addition, CD68+ macrophages markedly infiltrated in aging atrium, including cardiac-resident macrophages (CCR2- MCHIIlow and CCR2- MCHIIhi macrophages) and monocytes-migrated macrophages (CCR2+ macrophages). RNA-seq analysis showed Reg3γ was themost significantly varied differential gene, and the expression of Reg3γ was higher in atrium prone to AF with aging than in those non-prone to AF with aging. After overexpression of Reg3γ, both aging and young rats showed great atrial electrical and structural remolding, AF inducibility as well as inflammatory infiltration. In addition, we found that Reg3γ promoted the recruitment of BMDMs, production and secretion of inflammatory factors by qPCR and cytokine array panel. Then, we found Reg3γ regulated macrophages probably through JAK-STAT signaling pathway by GSEA analysis of RNA-seq. And the siRNA results confirmed that Reg3γ activated macrophages through the gp130-JAK1-STAT3 pathway. Conclusion Reg3γ recruits macrophages and activates them through the gp130-JAK1-STAT3 pathway, then promoting production and release of inflammatory factors, ultimately contributing to the development of aging related Atrial fibrillation.